In general, a cooking apparatus is an appliance that uses heat from a heater or microwaves to cook food. A cooking apparatus that uses a heater includes a cooktop, atop which a cooking vessel containing food to be cooked is placed. A cooktop includes an inner heater, and an outer heater provided at the outside of the inner heater. The inner and outer heaters are selectively operated to heat a cooking vessel according to the size of the cooking vessel (or more specifically, the undersurface area of the cooking vessel) placed on top of the cooktop.